Apparatus for manufacture of refractory shell molds

ABSTRACT

The disclosure relates to apparatus for systematically forming refractory shell molds including a plurality of independently movable shell pattern carrying units capable of movement in selected patterns on a runway for carrying patterns to selected fluid and particle materials treatment stations. The carrying units are coordinated in their movement to permit a plurality of stations to be served by more than one carrying unit.

United States Patent [72] Inventors William H. Trench Chester; Stanley C. Tingqulst, Sparta, both of, NJ. [21] Appl. No. 739,862 [22] Filed June 25, 1968 [45] Patented Aug. 31, 1971 [73] Assignee Howmet Corporation [54] APPARATUS FOR MANUFACTURE OF REFRACTORY SHELL MOLDS 5 Claims, 6 Drawing Figs.

[52] U.S.Cl 164/166, 164/26 [51] Int. CL B22c 13/08 [50] FieldolSearch 164/15,16, 18,23,24,25,26,154,157,165,166, 361; 18/26 R; 1 18/312 [56] Refeneum Cited UNITED STATES PATENTS 2,560,047 7/1951 York et a1...; 118/312 X AMMONIA LOAD UNLOAD STATION 22A STATION 2,889,805 6/1959 Freeder 118/312 X 3,208,868 9/1965 Strobe] et a1; 118/312 X 3,278,998 10/1966 Tingquist et al. 164/16 X 3,361,111 1/1968 Strobeletal ll8/312X FOREIGN PATENTS 139,370 11/1950 Australia Primary Examiner-J. Spencer Overholser Assistant Examiner-John E. Roethel AttorneyPennie, Edmonds, Morton, Taylor and Adams ABSTRACT: The disclosure relates to apparatus for systematically forming refractory shell molds including a plurality of independently movable shell pattern carrying units capable of movement in selected patterns on a runway for carrying patterns to selected fluid and particle materials treatment stations. The carrying units are coordinated in their movement to permit a plurality of stations to be served by more than one carrying unit.

26 HYDRAULIC SUPPLY UNIT LOAD UNLOAD STATION CONTROL CONSOLE PATENTEDIIIIABI IIIII I 3Q6O2'Z8 I SHEET 1 U? 5 FEGOQ I HYDRAULIC /26 29A: 5 SUPPLY UNIT AMMONIA CHAMBER STATION AMMONIA CHAMBER STATION LOAD UNLOAD UNLOAD STATION 22B STATION PARTICLE MATERIAL DUS'TWG STATION PARTICLE I MATERIAL OusTIAIO & sTATIOA-I D3 P TANK STATION a CONTROL. OOAISOLE U i3 0 ENVENTORS WILLIAM H. TRENCH STANLEY C. TENGQUEST ATTOW N EYS PATENTED AUB31 I97! Sum 2 or 5 INVENTORS WILLIAM H. TRENCH STANLEY C. TlNGQUIST BY 64 777,15, 22$ $4M AT ORNEYS wam PATENTED M831 I97! sum 3 OF 5 INVENTORS WILLIAM H. TRE

ATTORNEYS RATENTEH- AUB31 l97l 35022 saw u UF 5 INVENTORS WILLIAM H. TRENCH STANLEY C. TINGQUIST ATTORN EYS PATENIEU AUG31 IBTI $602,288

SHEET 5 BF 5 INVENTORS WILLIAM H. TRENCH STANLEY C. TINGOUIST awn-Law #7 MM ATTORNEYS APPARATUS FOR MANUFACTURE OF REFRACTORY SHELL MOLDS BACKGROUND OF THE INVENTION Shell molds for accurate metal castings are customarily made by shaping a pattern of the desired castings in wax or other fusible material and then forming a refractory shell on the pattern by dip-coating the pattern in a liquid suspension containing a finely divided refractory, thereafter further coating the pattern with a layer of larger refractory particle matter and finally causing the entire layer to harden by use of air or other gases. A Plurality of layers are formed in this manner. An accurate shell mold of the article to be cast is provided by eliminating the pattern from within the multilayered shell.

Prior apparatus for handling shell patterns during their coating and treatment have included indexing arrangements wherein a plurality of shells are handled in a sequential manner. Such an arrangement is shown in US. Pat. No. 3,278,998 issued Oct. 18, 1966. Prior apparatus for coating and treating shell molds have not provided nor been capable of providing sufficiently flexible treatment of the shell mold.

In handling patterns where their size and shape require special treatment, we have found that the existing equipment was not capable of sufficiently flexible operation. Larger patterns having detailed surfaces often require a longer period of fluid coating of refractory slurry or a thicker application of particle refractory materials to the liquid coating. The handling of larger patterns often requires longer gaseous curing of the coating.

It has also been found that the application of particle refractory materials such as sand, wood chips, zirconium silicate and aluminum oxide, to the coated pattern cannot be satisfactorily accomplished by dipping the pattern into a container of such materials. The use of aeration of the material to facilitate penetration of the pattern into the material has been used in the past but has not solved the problem of applying such coating to larger patterns.

SUMMARY OF THE INVENTION It has been found that the mounting of the patterns on independently controllable carrying units provides a'flexible and efficient apparatus for handling the patterns during their treatment.

Broadly, the presentinvention comprises a runway upon which a plurality of pattem-carrying units are positioned for coordinated movement independent of one another. Pattern treatment stations are positioned adjacent the runway and are adopted to receive the patterns for fluid and particle material treatment in selected sequences to form multi layered shell molds on the patterns. Pattern holding and positioning devices raise, lower and rotate the patterns as required to properly dip, coat and position the patterns at the stations. The units, the holding and positioning devices and the stations are preferably operated through a central control unit.

It is a feature of the apparatus that the pattem-carrying units are selectively movable to carry the patterns to be coated to various treatment stations as necessary to produce a multilayered shell mold on each pattern.

It is also a feature of the invention that the refractory material stations provide for discharging the refractory material down onto the pattern which is mounted for rotation during such coating to provide for a substantially uniform ap plication of material to the pattern.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a schematic plan view of the apparatus;

FIG. 2 is a side elevational view taken along line 2--2 of FIG. I;

FIG. 3 is a side elevational view taken along line 33 of FIG. 1;

FIG. 4 is a sectional elevational view of the dusting station with a pattern positioned for dusting;

FIG. 5 is an elevational view taken along line 5-5 of FIG. I; and FIG. 6 is a sectional view taken along line 66 of FIG. 5.

Referring further to the drawings and particularly to FIGS. 1 and 2, the apparatus includes two pattern carrying units 9A and 98 each having a carriage 10A and 10B positioned on a semicircular carriage runway I 11 which are, respectively, guided by arms 12A and 12B mounted for horizontal movement about post 13. Post 13 is positioned in and supported by pillar 14 which is secured to foundation 15 through plate 17.

Carriages 10A and 103 have frames 18A and 18B axles and 19A and 19B mounted on one end portion of the frames and carrying pairs of wheels 20A and 20B and third wheels 21A and 21B positioned to support the other end portion of the frames. Hydraulically operated motors 23A and 23B are positioned on frames 18A and 18B to drive the respective carriages along runway 11 which is elevated above the foundation by stand 24 which stand also serves to house control circuit wiring. Motors 23A and 23B are supplied with oil, water or other suitable liquid'under pressure to supply energy to the motors in a controlled manner. Alternatively, electric motors may be used with suitable hydraulically operated controls. Motors 23A and 238 have associated with them gearing arrangements (not shown) for driving the axles to move the carriages on the runway. Hydraulic supply lines 25 are connected to hydraulic supply unit 26 in accordance with known arrangements for driving hydraulic motors and particularly are arranged to provide hydraulic supply such that the'motors can be reversed to permit movement of the carriages in either direction.

Hydraulic supply unit 26 is controlled by control console unit 28 to cause carriage 10A to move into and out of ammonia chamber station 29A and to cause carriage 108 to move into andout of its ammonia station 293. Both carriages are, in accordance with the control system, capable of movement to all wood chips dusting stations 30A and 30B and dip tank station 32. The unloading stations 22A and 228, like the ammonia stations, serve only their corresponding carriage; however, it is contemplated that arrangement and design of the stations could also provide for each carriage to be capable of serving each station. Arms 12A and 12B are pivotably connected to post l3 at one end and are fixed to carriages 10A and 108 at the other end to pivotally guide the carriages as they move on runway 11. The arms also serve the function of supporting the pattern holding and positioning devices 33A and 33B.

The pattern holding and positioning devices 33A and 33B are similarly constructed with device 33A having a spindle support 34 which includes upstanding plates 35, outer crosspieces 36A and inner crosspieces 37A. Upstanding plates are positioned parallel to one another and spaced apart a distance sufiicient to permit pivotable spindle sleeve bearing 39 to be positioned between the plates. Stationary axle 40 secured to the plates 35 passes through holes in sleeve 39 to permit the sleeve and the spindle rotatably positioned 41 within to be pivoted. Spindle extension 43 has a pattern 44 detachably affixed to it. Any suitable detachment device may be used providing that the pattern may be readily attached and detached to the spindle extension and further providing that the pattern is firmly held during its movement to the various stations. Spindle 41 is mounted on a suitable bearing surface within sleeve 39 and has its inner end connected to drive sprocket 46 which in turn is driven through chain 47 by motor unit 48. Motor unit 48 is secured to sleeve 39 through bracket 49. A protective cover 51 surrounds chain 47 and the associated sprockets.

Pattern holding and positioning device 33A also includes sleeve turning unit 52 having crank 53 attached at one end axle 40 and pivotable connected to piston rod 54. Rod 54 is reciprocated by the appropriate application of hydraulic pressure to cylinder 55 which has a piston (not shown) positioned therein and attached to rod 54. Cylinder 55 is pivoted at axis 56 to permit rod 54 to move through its full travel from the down position of spindle 41, as shown in FIG. 2, to a position at least 20 above the horizontal and piston 54 has moved outwardly to a position adjacent crosspiece 36. After the pattern is coated at the dip tank station 32, it is raised, moved to various angles as required and is rotated to permit the liquid coating to run down and over the surface of the pattern to accomplish uniform coating. It should be noted that the pattern is first coated and treated and thereafter the coated pattern is again coated and treated. As used herein the term pattern where appropriate often refers to a pattern having one or more coatings.

Electrical position control unit 57 (not shown) actuates valves for selectively applying hydraulic pressure to either side of the piston secured to rod 54. Cylinder 55 is supported on arm 12A through axis 56 and vertical wing supports 60. F lexible mounts 61 provide further support while permitting the cylinder to turn about its axis 56. Cover 62 is secured to arm 12A which includes outer section 63 and inner section 64 connected by hinge 65 to accommodate for variations in carriage runway elevation.

Turning to FIG. 3, dip tank station 32 includes larger dip tank 69 supported by stand 70 with smaller dip tank 66 positioned within the larger tank and resting on stand 70 in such a manner that it may readily be removed when a larger casting requires use of the larger tank. Tank 66 contains refractory slurry 67 which is a liquid including finely divided refractory particle and a binder. The viscosity of the slurry may be varied by use of a heat exchange unit (not shown) to permit a coating or desired thickness to be applied. Pattern 44 is preferably rotated as it is being dipped to cause the slurry to be applied to all the surfaces of the pattern. After such application in the dip tank, the pattern is raised and rotated in either or both directions to assist in distribution of the liquid slurry on the pattern.

In FIG. 4, particle material dusting station 30A, which has substantially the same construction as corresponding station 30B, includes structural frame 73 positioned in foundation plate 74. Collection bin 75 is supported by frame 73 and foundation which has a recess 76 to provide for removal of the dusting material from the bottom of bin 76. A bucket conveyor system 77 conveys the dusting material from lower reservoir 78 and elevates the material in buckets 79 to unloading housing 80 where the buckets are dumped into shute 82. Material flowing down shute 82 flows first through upper guide 83 and then through lower guide 84, both guides directing the material toward pattern 44. Material which does not stick or lodge onto the pattern passes into collection tank 75, flows to reservoir 78 and is recirculated. Bucket conveyor 77 includes lower sprocket 85, chain 86 and an upper sprocket (not shown which is driven by sprocket drive system 88.

In FIG. 5, ammonia chamber station 29A, which is constructed substantially the same as station 29 includes chamber 89 having a hood 87 and exhaust conduit 91 with a damper 92 to regulate the flow of ammonia gas from the chamber. Ammonia gas or other suitable gases are introduced into the chamber to cure and jell the slurry coating on the pattern. The chamber 89 is defined by sheet material panels 90 on chamber frame 91 and has two openings therein. A side opening 92 is closable by sliding door 93 which is slidable in vertical guides 94 on either side of the opening 92. Door 93 has eyelet mounts 95 connected to its upper surface for hoisting by two cables 92 (one cable is not shown) that are moved up and down by a winding arrangement (not shown). The inward panel 90 has a slot opening 98 for receiving spindle extension 43 as the pattern 44 is moved into the chamber 89. Referring also to FIG. 6, slot opening 98 has cover 100 secured to panel 90 by hinge 101. Cable 102 which is moved over pulley 103 be any suitable mechanism lifts and lowers the cover 100 to cover substantially the entire slot opening during operation of the ammonia station. Cable 102 is connected to cover 100 through loop 105.

In the operation of the apparatus, the pattern-carrying units 9A and 9B are caused to be moved back and forth on the runway by operation of the control console 28 which in turn operates the hydraulic supply unit 26 and suitable controls for operating the various stations. The carriages are moved to their corresponding ammonia and unload stations and the other stations in any sequence required for the manufacture of the type and composition shell mold desired. The carriages ore operated, preferably with an automatic interlock mechanism, to prevent collision or other interference between them. The interlock mechanism may be arranged to require one carriage to move to its ammonia station before the second carriage is operable to prevent operator error in the sequence of treatment steps. In the manufacture of a typical shell mold, the pattern 44 is placed on the spindle extension 43 of either one of the carriage units. The control console is operated to move the carriage unit to a position adjacent dip tank station 32 where the pattern holding and positioning device 33 is operated to lower the pattern into the slurry contained in the dip tank 66. Spindle 41 is caused to rotate as the pattern is raised to facilitate the spreading and proper coating of the slurry on the pattern. The carriage is then moved to one of the dusting stations 30 where conveyor system 77 is energized to dust the slurry-coated pattern with refractory or other suitable material. The pattern is positioned in a horizontal position and preferably rotated during the dusting or sanding operation.

After the dusting step, the pattern is moved into its ammonia chamber station for treatment of the coating or coatings on the pattern to cause jelling and curing of the slurry material. After the chamber door, cover and damper are closed ammonia is introduced into the chamber. Ammonia is drawn off through hood 87 to a reservoir where it is collected and thereafter condensed and stored for reuse. After completion of the ammonia curing step, the damper is opened and the pattern is purged of ammonia by flowing air through the chamber. The pattern is removed from the chamber for further coating with slurry and granular materials. A number of coats may be applied to form a desired shell mold. When the shell mold is completely formed on the pattern, the pattern and its surrounding mold are removed at its unload station.

We claim: 1

l. A refractory mold-forming apparatus for automatically coating a plurality of mold patterns comprising a. an arcuate runway including a curved support surface positioned in a generally horizontal plane, b. a pivotable mounting means spaced from the runway, c. at least one pair of pattem-carrying units pivotably mounted on the mounting means with each unit being capable of independent pivotable movement on the runway surface, d. holding and positioning means on each unit of the pair for holding and positioning a mold pattern, said means in turn comprising i. means for elevating and lowering the pattern, and ii. rotatable means for rotating the pattern, e. a common dip tank adjacent the side of the runway opposite the mounting means into which the mold pattern carried by each one of a pair of the carrying units may be clipped, a plurality of gas and particle treatment stations positioned adjacent the arcuate runway which in turn comprise i. a plurality of gas-treating stations with at least one such station positioned on each side of and spaced from the common dip tank; and

ii. a plurality of particle treatment stations with at least one such station positioned between each gas treatment station and the common dip tank,

g. moving means for pivotably moving each one of the pair of the carrying units independently of the other one of the pair to and from the common dip tank through their respective gas and particle treatment stations, and

h. control means positioned remotely from the units for controlling the moving means and for controlling the holding and positioning means whereby mold patterns are selectively positioned, elevated and rotated to permit treatment at selected stations.

2. The apparatus of claim 1 in which the positioning means for moving each carrying unit is positioned on the unit.

3. The apparatus of claim 1 in which each particle material treatment station includes a sanding station for sanding the pattern in turn comprising a. vertically disposed shute means having upper and lower portions and having an access opening therebetween to permit the pattern to be positioned within the shute for treatment,

b. delivery means for delivering the sand to the upper portion of shute where the sanding material is caused to fall down onto and around the pattern and c. collecting means in the lower portion of the shute for collecting sanding material not passing around the pattern.

4. The apparatus of claim 1 in which each gaseous treatment station includes agaseous chamber station for treating the coated pattern with gas in turn comprising a. a chamber for containing the gas, b. an access opening in the chamber to permit the pattern to be moved into and out of the chamber, and c. closure means for closing the access opening. 5. The apparatus of claim 1 in which the particle treatment stations comprise i. vertically disposed guide means having upper and lower portions and having an access opening therebetween to permit the pattern to be positioned within the opening and to be moved up and down within the opening, ii. delivery means for delivering the sanding material to the upper portion of the guide means from which sanding material is discharged to cause it to engage with the pattern, and iii. collecting means in the lower portion of guide means for collecting sanding material not remaining in engagement with the pattern. 

2. The apparatus of claim 1 in which the positioning means for moving each carrying unit is positioned on the unit.
 3. The apparatus of claim 1 in which each particle material treatment station includes a sanding station for sanding the pattern in turn comprising a. vertically disposed shute means having upper and lower portions and having an access opening therebetween to permit the pattern to be positioned within the shute for treatment, b. delivery means for delivering the sand to the upper portion of shute where the sanding material is caused to fall down onto and around the pattern and c. collecting means in the lower portion of the shute for collecting sanding material not passing around the pattern.
 4. The apparatus of claim 1 in which each gaseous treatment station includes a gaseous chamber station for treating the coated pattern with gas in turn comprising a. a chamber for containing the gas, b. an access opening in the chamber to permit the pattern to be moved into and out of the chamber, and c. closure means for closing the access opening.
 5. The apparatus of claim 1 in which the particle treatment stations comprise i. vertically disposed guide means having upper and lower portions and having an access opening therebetween to permit the pattern to be positioned within the opening and to be moved up and down within the opening, ii. delivery means for delivering the sanding material to the upper portion of the guide means from which sanding material is discharged to cause it to engage with the pattern, and iii. collecting means in the lower portion of guide means for collecting sanding material not remaining in engagement with the pattern. 